Electrical Properties of SiGe/W Plate Node in DRAM Capacitor

Recently DRAM(Dynamic Random Access Memory) industry is continuously scaling down to improve productivity and create low power memory products. This trend reduces the capacitance for storing data and increases the unwanted parasitic capacitance, which causes problems in data storage of DRAM. In addition, the plate structure of the node on the current DRAM capacitor further reduces the data storage capacity by causing voltage noise during product operation. In this paper, electrical properties were evaluated using SiGe/W(tungsten) structure instead of the existing SiGe(silicon germanium) plate, based on the fact that when the resistance of the plate node on the capacitor decreases, the plate noise can be improved during product operation by RC model. W was deposited on the high-doped SiGe by PVD(Physical Vapor Deposition), and it was confirmed that an Ohmic contact between SiGe and W was formed. Sheet resistance and contact resistance were decreased by 86.6% and 51.1%, respectively, compared to the existing SiGe plate structure under the voltage condition of 3 volts. As a result, it was confirmed that the value of capacitance for storing data increased by 20%. In order to confirm the improvement of failure, we conducted a test that caused plate noise by continuously inversion of adjacent data, and confirmed that the failure was improved by 36% in the SiGe/W plate structure. Figure 1